P0442 means the EVAP system has detected a small leak — smaller than the large leak of P0455 but still enough to let fuel vapors escape. Small leaks are harder to find and often require a smoke test.
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What's the difference between P0442 and P0455?
P0442 is a small EVAP leak; P0455 is a large one. Both are EVAP leaks, but P0442 is harder to find because the leak is smaller.
How do I find a small EVAP leak?
Start with the gas cap. If it's tight and the code returns, a smoke test is the most reliable way to find small EVAP leaks without guessing.